喷气涡流纺纱线细节产生机制分析

通过数值计算对喷气涡流纺喷嘴内部流场衰减规律进行探讨。讨论加捻腔中纤维的受力情况及涡流作用下的运动状况;建立倒伏在空心锭上的纤维自由端绕空心锭旋转的临界角速度与进入纱尾的纤维头端长度、纤维半径等参数间的函数关系,以临界角速度作为衡量纤维头端是否被抽拔的依据,解释喷气涡流纺落纤、成纱细节产生的原因。临界角速度随进入纱尾纤维头端长度的增加而增大;纤维半径越大,临界角速度越小,在同一喷嘴气压下,半径大的纤维纺纱时落纤、成纱细节较多;增加喷嘴气压对成纱强力有利,超过某临界值落纤、成纱细节增加,对成纱质量不利;增加喷嘴内部负压,适当减小前罗拉与空心锭的距离可减少落纤、细节的产生。

Analysis of the cause leading to generation of thin places on the air jet vortex spun yarn

The attenuated law of flow field inside the nozzle block of the air jet vortex spinning is investigated by the method of numerical computation.Force analysis about a separated fiber in twisting chamber and the movement of a separated fiber affected by vortex in twisting chamber are discussed.The function relationship between the critical angular velocity of the fiber′s open-end twined over the hollow spindle and rotated around the air jet vortex spun yarn and the length of the leading fiber ends inside the yarn′s trail,fiber radius and so on is constructed.The critical angular velocity may judge whether the leading fiber ends pulled out the yarn′s trail or not,which can explain the generation of waste fibers and thin places.The critical angular velocity increases along with increasing the length of the leading fiber ends inside the yarn′s trail.On the condition of the same nozzle pressure,the fiber radius is bigger,waste fibers and thin places of the air jet vortex spun yarn are severer.Increasing nozzle pressure firstly can enhance the yarn strength,however,when the nozzle pressure exceeds the critical point,and waste fibers and thin places become more,which make the yarn properties deteriorate.Increasing negative pressure inside the nozzle and decreasing properly the distance from the front roller to the hollow spindle can decrease the generation of waste fibers and thin places.